The Okapi project’s main purpose is to architect a set of building blocks for the creation of larger open source localization and translation tools. But many Okapi components are generic enough to be of interest to the text mining, natural language processing, and text retrieval communities. Okapi’s many text filters (HTML, Properties, XML (ITS XPath-based rules), OpenXML, ODF, Regex etc.) provide a straightforward way to access the text of multiple document formats. Its document events and pipeline can be made to integrate with other frameworks such as UIMA, LingPipe, OpenPipeline, OpenNLP, GATE, and Lucene. The advantage of Okapi’s text filters is that not only is text extracted, but all non-textual formatting is preserved. It is possible to decompose a document into events, process them via the pipeline, and then rebuild the input document without loss. Structural information can be added to Okapi document events so that tables, lists, links, titles etc. are grouped together and treated as a unit. This is useful when context based on a “universal” document structure is needed. The Okapi event model supports user configurable annotations, similar to UIMA, but simpler and more restricted in scope. User can annotate spans of text or add new resources such as translation memory matches, terminology, token types, or part of speech information.
